Landslides and human interference in Darjiling Himalayas, India

Abstract

Landslides are among the nature's primarily ways of adjustment to slope stability. In Darjiling Himalayas the process has been intensified by human interference mainly through rapid deforestation, incorrect construction procedure and unplanned tapping of natural resources. The present paper aims at investigating the occurrence of landslides mainly due to human intervention. For analyzing the acuteness of the problem, important events of landslides over time, landslide susceptibility map using traditional check-list and investigation of the nature of human intervention for landslide occurrences have been carried out. From the study it is found that extreme rainfall events of consecutive days accumulating an amount of 1000 to 1200 mm, coupled with deep weathering in susceptible structure could trigger to 5 to 10 m-thick landslides. Being saturated with percolating rainwater, such slopes even with a rainfall 50 of mm/h would cause disastrous landsllides. Common occurrence of landslides is found along the springs, where thick debris is removed along the slope, ontop of the bedrock.. Generally deforested urbanized tracts, illegal coal mining sites, tea gardens, artillery roads connecting hills with the plains are the most susceptible areas to sliding.